But you have to be careful to not sand too much off. Just sand them enough to rough up the surface a little (called adding a little bit of 'tooth') for the new paint to adhere. I used a general purpose white acrylic spray primer that was available at my local Ace hardware store. I think they call it fast-dry something or other. I then used their high-gloss white spray paint for the painting.
A lot of people recommend brushing the paint on, but I feel pretty good about how ours came out using the spray cans. I hated the look of brush strokes, and I wasn't wild about the look that even a short-nap roller left. I started to think about spray cans after I used some to prime the drawer fronts that we had.
Here's a 'before' of what the cabinets looked like (the room is very dark, so bear with me):
If you copy those links and paste them into your browser's address bar, you should be able to see them. They were taken from different angles, but the cabinets are all the same. I also added some new 'stock' cabinets to the mix and sanded and painted those the same white. New hardware really helped change the look of everything.